Yahoo! countersued! by! Facebook! in patent! spat!

The social networking giant has not taken kindly to its web rival's patent volley in the final weeks before its IPO: it has denied any infringement of Yahoo!'s intellectual property and is counter-suing using ten of its own patents.

"From the outset, we said we would defend ourselves vigorously against Yahoo's lawsuit, and today we filed our answer as well as counter-claims against Yahoo for infringing ten of Facebook's patents," Ted Ullyot, general counsel for Facebook, said in an emailed statement.

"While we are asserting patent claims of our own, we do so in response to Yahoo's short-sighted decision to attack one of its partners and prioritise litigation over innovation."

The filing alleges that pretty much everything about Yahoo! is infringing on Facebook in one way or another, including its home page, content optimisation and relevance engine, its Flickr photo sharing service and its ads.

Yahoo! might have thought that Facebook was a pretty juicy target for some quick cash, since it wouldn't want to do anything to upset its coming-out day (expected any time now) and it hadn't banked too many patents of its own yet.

Clearly the social network has decided not to take the easy way out and settle the case before going public, indicating that it doesn't think Yahoo!'s legal machinations can dent the excitement of investors.

Yahoo!'s patent lawsuit was widely seen as an opportunity for new CEO Scott Thompson to boost revenues quickly as the ailing web firm continues its struggle to restructure into a money-making business again. Whether it will want to stick it out in the long term remains to be seen.

Yahoo! told The New York Times that Facebook's claims are groundless.

"We have only just received Facebook’s answer and counterclaims, but on their face we believe they are without merit and nothing more than a cynical attempt to distract from the weakness of its defence," the firm said. ®